Process for fractionation of



May 16., 1939.

lPROCESS FOR FRACTIONATION OF SULPHONIC COMPOUNDS E. R. P. E.R-ETAILLIAU 2,158,680 I Filed Aug. 17, 1956 Patented May 16, 1939PROCESS FOR FRACTIONATION 0F SULPHONIC COUNDS Edmond R.. P. E.Retailliau, Wood River, lll., as-

slgnor to Shell Development Company,

Francisco, Calif., a corporation of Delaware Application August 17,1936, Serial No. 96,482.

Sclaims.

'I'his invention relates to the fractionation of sulphonic compounds,particularly of the type produced in treating parainic mineral oils withstrong sulphuric acid. The term sulphonic compounds as herein usedrefers to free sulphonic acids and/or salts thereof. Alkali salts ofsulphonic acids are widely used as detergents, emulsiers, wettingagents, binders, substitutes for Aasphalts, reproofers, etc.

It is known that when mineral oils are treated with strong sulphuricacid several types of sulphonic acids may be produced. One type which isreadily soluble in hydrocarbon oils as well as in many aqueous organicsolvents is known as mahogany acids. Another type which is 4less readilysoluble or insoluble in hydrocarbon oils but soluble .in water andaqueous organic solvents is known as green acids.

at least partly soluble in hydrocarbon oils in the presence of mahoganyacids.

The alkali salts of these acids have solvent` properties quite similarto those of the free acids. Because of their solubility both inhydrocarbons and aqueous solvents, mahogany salts are especiallyvaluable as detergents and emulsiers.

Inasmuch as different types of sulphonic compounds have widely dierentproperties and uses. it is highly desirable to separate them from each.other as fully as possible. It is an object of this invention toprovide a process for separating mixtures of diierent types of sulphoniccompounds, which by virtue of the mutual solutizing influence of theircomponents are completely soluble in hydrocarbon oils, only a fractionof which, however, is soluble therein when separated, the other fractionbeing substantially insoluble in hydrocarbon oils. It is a furtherobject to produce in a simple mannensubstantially pure true oil solublesulphonic compounds which consist essentially of a single type and whichare substantially free of sulphonic compounds dimcultly soluble in oil.

I have discovered that hydrocarbons consisting A of a simple aromaticnucleus to which is attached at least-one long aliphatic side chain, forinstance, as cetyl benzene or cetyl xylene, yield upon sulphonationsulphonic acids which are more easily soluble in hydrocarbon oils,particularly aromatic hydrocarbon solvents, andtheir salts exhibit bet#ter detergent and emulsifying properties than sulphonic acids and saltsrespectively 'produced from hydrocarbons of about the same number ofcarbon atoms comprising a more complicated aromatic nucleus of the typeof naphthalene, di-

Certain green acids, although insoluble in hydrocarbon oils, became (Cl.26a-504) phenyl, anthracene, chrysene, etc. with at least one long sidechain or a simple nucleus with many short side chains such as dioctylbenzene or trihexyl benzene.

Depending upon the nature of mineral oils treated and the strength ofthe sulphuric acid used, varying quantities of mahogany and green acidsare produced. Relatively high yields of mahogany acids are. obtainablefrom paramnic oils boiling above kerosene and containing the desiredtype of sulphonatable hydrocarbons, such as Pennsylvania wax distillatesand lubricating oils, or

vrafilnates produced in the solvent extraction'of mixed base relativelyhigh boiling oils, while socalled naphthenic oils such as Gulf Coastaland similar oils, extracts of mixed base oils, or relatively low boilingoils, in general, yield largely green acids.

In order to produce sulphonic acid salts of the highest detergent andemulslfying qualities I have invented two lines of approach. AI maysynthetically produce the desired hydrocarbons, for instance by reactingchlorinated paraliin wax with benzene or a homologue thereof in thepresence of a Friedel-Crafit catalyst such as aluminum chloride, zincchloride, boron uoride, ferric chloride, phosphorus pentoxide, etc.under conditions to produce benzene derivatives having at least oneparain-like hydrocarbon attached as va side chain; or by cracking in thevapor phase or preferably dehydrogenating paraffin wax and fractionallydistilling the resulting product under conditions to produce long chainolei'lnes of l0 or more carbon atoms, and ,condensing same with benzenein the presence of a suitable condensation catalyst such as phosphoricacid, sulphuric acid,vphosphorus pentoxide, etc. to form similarlongchain alkylated benzene derivatives. The products of alkylation arethen sulphonated to produce sulphonic acids, and the acids or theirsalts are separated from impurities and unreacted hydrocarbons by knownmethods.

The other line of approach with which this invention is particularlyconcerned, comprises sulphonating a suitable pareinicmineral oil of thetype afore described and separating the resulting sulphonic acids ortheir salts from unreacted sulphuric acid, vmineral oil, and sludge byknown methods. Due to the solutizing eec't which the truly oil solublesulphonic compounds exert on less oil soluble sulphonic compounds theoil phase after separation contains, together with oil soluble sulphoniccompounds, a considerable quantity of sulphonicl compounds which. bythemselves, are substantially insoluble in the oil. Sulphonic compoundsisolated from the oil phase are thus mixtures containing varyingquantities of water-soluble sulphonic acids or salts which are diicultlysoluble in hydrocarbon oils. In my process I separate mixtures oftrulyxoil soluble and difculty oil soluble sulphonic compounds byextracting such mixtures either in the acid, neu- .tral or alkalinestate simultaneously with two organic lsolvents which are substantiallyimmiscible with each other, one being hydrophobe and the other beinghydrophile, under conditions to eect a distribution of the compounds inthe two solvents, separating the solutions so obtained from each otherand separating the solvents from the acids or salts in any suitablemanner such as by salting out, or preferably by distillation. Toincrease the immiscibility of the hydrophobe and hydrophile solvents,and to raise their relative solvent powers and selectivity for the twotypes of sulphonic compounds, I usually add a substantial amount ofwater to the hydrophile solvent.

If desired, the mixture of compounds may be iirst dissolved in onesolvent, and the solution so obtained may then be extracted with theother solvent under conditions to eiect a separation. My preferredprocedure consists of dissolving the mixture i'irst in the hydrophilesolvent and extracting the resulting solution with the hydrophobesolvent.` in this last manner separation or" mahogany and green acids orsalts thereof is most easily achieved, since both types of compounds aresoluble independently oifjeach other ln the hydrophile solvent, but onlythe true mahogany compounds are readily and independently soluble in thehydrophobe solvent.

Salts separated from the extract contained in the hydrophobe solventpossess the desired high. detergent and emulsifying properties.

Suitable hydrophobe solvents are aromatic low boiling hydrocarbons asbenzene, toluene, xylenes, ethyl benzene, etc. although aliphatic andnaphthenic hydrocarbons as naphtha, petroleum ether, cracked andstraight-run gasoline distillates, gasoline extracts, etc. may also beused. Halogenated hydrocarbons such as carbon tetrachloride, di-duordi-chlor methane, chloro v form, ethyl chloride, di-chlor ethylene,tri-chlor ethylene, propyl chloride, di-chlor propane, etc. are suitableas well. Aromatic hydrocarbons and in particular toluenaor mixtures ofhydrocarbons containing high percentages oi aromatic hydrocarbons arepreferred because they appear to have the greatest solvent power for thedesired sulphonic acids or salts.

The hydrophilic solvent which is used to dissolve or "seep in solutionthe less desirable sulphonic acids or soaps may be selected from thegroup of oxyand/or aminol hydrocarbons or substituents thereof, which atordinary room temperatures are miscible with water preferably in allpropertions and which at least in the presence of water aresubstantially immiscible with hydrophobe solvents. This group comprisesthe lower mono-hydric alcohols of less than 4 carbon atoms; poly-hydricalcohols as ethylene glycol, glycerine; lower ketones as acetone, methylthan of their salts; selective solvents of the type used in thefractionation of hydrocarbon oils aisaaeo such as liquid SO2, furfural,di-chlor ethylf ether, phenol, cresilic acids, nitro benzene, acrilicaldehyde, croton aldehyde, etc. may have a limited application if usedin combination with a hydrophobe solvent which is only partiallymiscible or preferably substantially immiscible therewith.

'I'he attached drawing shows flow diagrams of my process; Figure 1presents diagrammatically a series of treating steps which may beemployed in my process, While in Figure 2 a method of extraction isshown which is applicable in connection with the treating procedure asshown in Figure 1.

Referring to Figure l, suitable mineral oil heavier than kerosene istreated with strong sulphuric acid which may or may not be fuming, intreatervI according to established procedures such as are, for instance,practiced inthe manufacture of medicinal oils, parafiinum liquidum,transformer oils, etc. The acid may be added in one or several dumps,and sludges may be withdrawn after each dump by settling, centrifuging,or precipitating with a nely divided solid as clay, diatomaceous earth,etc.

The substantially sludge-free but acid-reacting oil containing oilsoluble sulphonic acids and a small amount of entrained unreactedsulphuric acid is neutralized in treater II Vpreferably with an alkalimetal hydroxide, although ammonia or alkali earth and other metalhydroxides may often be used instead. If sludge is formed, same may bewithdrawn. The neutralized oil is now extracted in an extraction unit Iwith an aqueous organic hydrophile solvent of the group hereinbeforedescribed. The most commonly applied solvents are 50% aqueous ethylalcohol or 85% aqueous ethylene glyl. The extraction is car ried outunder conditions to eiect a substantially complete transfer of thesulphonic acid salts from the oil to the hydrophile solvents. lThis caneasily be achieved in a multi-stage countercurrent extraction system.The resulting mineral oil, free from sulphonic acid soaps, is withdrawn,and the hydrophile solution containing sulphonates and small quantitiesof sulphate and mineral oil is extracted in extraction II with arelatively small'amount of a non-aromatic hydrocarbon solvent such asnaphtha, preferably straight run from a parainic crude, butane, pentane,hexane, cyclohexane, etc. under conditions todissolve the mineral oiland to leave the salts substantially completely in the hydrophilesolution. To accomplish this it is desirable that the ratio ofhydrocarbon to hydrophile solvents be below about 1:2, and theextraction is preferably not carried out in countercurrent. Ordinarybatch washing at temperatures not substantially above ordinary roomtemperature is usually quite suitable. If desirable, the concentrationof salts in the hydrophile solvent'prior to extraction in unit I may beincrease by evaporating at least a portion of the hydrophile solvent.

The de-oiled hydrophile solution is now further extracted in anextraction unit III with a hydrophobe solvent of the type described,under conditions to transfer a substantial portion of the sulphonatescontained inthe hydrophile solution to the hydrophobe solvent. This maybe achieved by counteriowing the two solvents, if desired in severalstages. In Figure 2 anillustrative diaf gram of a suitable extractionprocess .is shown in which the de-oiled hydrophile solution entersthrough line l, into-an extraction tower 2 near its top, while thehydrophobe solvent, such as toluene, enters through line 3 into thelower part of tower 2. The hydrophobe solvent rises to the top,dissolving at least a portion of the preferred truly oil solublesulphonates together with a relatively small portion of hydrophilesolvent and a trace of dimcultly oil soluble sulphonates. This extractis transferred through line 4 to extraction tower 5 in which it iswashed with water from line 6 to remove dissolved hydrophile solvent andsmall quantities of oil insoluble sulphonates. The hydrophobe extractincolumn 5 which now contains almost pure truly oil soluble sulphonates ofthe highest detergent and emul sulphonic compounds are increased. Washwater not returned to column 2 may be withdrawn through line 8 togetherwith the hydrophile extractedA solution from column 2. Green sulphoniccompounds contained in the latter may be recovered by known methods,such as salting out or evaporation.

While I have described a particular method of `producing and handlingthe sulphonic4 compounds it shall be understood that this method ismerely illustrative; For instance, the neutralization in treater II maybe omitted or be carried out at a later stage, and at least one of theextractions in extraction units I to III may be carried out in the acidcondition. However, to avoid corrosion diiiculties and becausev of moreefcient separation due to the fact that the less desirable freesulphonic acids are somewhat more soluble in hydrocarbon oils than theirsalts, it

. is usually preferred to neutralize the oil or make .it slightlyalkaline at the earliest opportunity.

The de-oiling step in extraction unit 1I, while very desirable, is notessential in my process. Failure to remove entrained or dissolvedmineral oil will cause the desired truly oil soluble sulphonic compoundsto be contaminated therewith after removal of the hydrophobe solvent. Iidesired, a separation oi the desired product and oil may be carried outby extracting the hydrophobe solution with an aqueous hydrophile solventof the Atype described under conditions to transfer substantially allsulphonic compounds contained in the former to the hydrophile solventwhile leaving the mineral oil in the hydrophobe solvent. The puriedsulphonic compounds may then be recovered from the hydrophile solutionby'evaporatlng the solvent therefrom.

Instead of starting my process with mineral oil and sulphuric acid, Imay begin with prepared mahogany salts such as commercial mahoganysalts, which usually contain from about 20 to 30% mineral oil, up to 5%of sulphate, up to 10% of naphthenic and fatty acid soaps, varyingpercentages of moisture, and a remainder which consists of varyingproportions of truly oil soluble and dimcultly-oil soluble sulphonates.The content of-the truly oil soluble sulphonates in the remainder isusually between the approximate limits of about 30 to '70%. Preferably,I first dis-` solve the mahogany salt in an aqueous organic hydrophilesolvent. .The resulting solution may then be de-oiled and the de-oiledsolution is extracted with a hydrophobe solvent as described.

As hereinbefore explained de-oiling as a separate step. may be omitted,particularly if a hydrophile solvent is used for dissolving the saltwhich has a low solvent capacity -for mineral oil in the presence ofdissolved sulphonates, such as 85% aqueous ethylene glycol, and whichpermits separation of at least a portion of the oil from the resultinghydrophile solution by settling or centrifuging; or de-oiling may becarried out by reextracting the salt in the hydrophobe solution with ahydrophile solvent, as described.

Other impurities such as naphthenic and fatty acid soapsas well assulphates being preferentially soluble in hydrophile solvents are littleextracted by hydrophobe solvents and do not contaminate to any extentthe hydrophobe solution of the desired sulphonic acids or salts.

As an alternative procedure a commercial mahogany salt may be dissolvedin a suitable hydrophobe solvent-and the resulting solution is treaterpreferably in counterfiow with an aqueousorganic hydrophile solventunder conditions to extract only that portion of the salt which is leastsoluble in hydrocarbons and to leave the true oil soluble salt in thehydrophobe solvent.

The yields of true oil soluble sulphonic acids or salts obtainable by myprocess obviously depend primarily on the composition of the oil solubleacid or salt mixture. In a particular instance,'a commercial mahoganysalt of the following composition was subjected to my process:

This salt was dissolved in aqueous 85% ethylene glycol to make a saltsolution of. about 20%. The resulting solution was washed twice withabout 20% by volume petroleum ether to remove mineral oil and theremaining solution was then thoroughly extractedwith toluene. Thetoluene extract after evaporation to dryness amounted to 35% by weightof the original mahogany salt. It was completely soluble in all mineraloils including paraillnum liquidum, had excellent detergent qualities,and produced very stable emulsions which did not separate appreciablyafter several days oi standing.

The sulphonates remaining in the glycol were then recovered byacidifying the solution and extracting it with a large volume ofpetroleum ether. sulphonic naphthenic and fatty acidswere dissolved inthe petroleum ether and separated from sulphuric acid. The petroleumether solution was then 1re-extracted with 50% aqueous alcohol todissolve sulphonic acids and to separate them from naphthenic and fattyacids. The alcohol solution was neutralized and evaporated to drynessyielding 16% of a sulphonic acid salt which was insoluble in hydrocarbonoils, had' poor detergent qualities, and produced emulsions whichrapidly settled out.

In the following table the: emulsifying qualities of the originalmahogany salt and the two salt fractions obtained therefrom arecompared. The emulsiying test consisted of dissolving 10 grams of thesalt to-be tested in 90 grams of a water in a mechanical shaker forthree minutes.

-allowing the mixture to stand, and notingits condition at various timeintervals.

ties from a substantially oil-free mixture y of sulphonic compoundshaving varying detergent Origin of the sulphonate Original mahogany com-Toluene soluble salt Toluene insoluble salt used marcial salt fractiontraction Original condition of the White milky emulsion White milkyemulsion Hardly any emulsion at all.

am on. After l2 hours Cream appears on top Homogeneous throughout.--

Complete separation after 5 minutes.

After 2i hours 1.1 ccs. of cream on top 0.2 ce. of cream on top. Alter48 hours No oil has separated in this No. oil has separated in thisemulsion. Aqueous layer` emulsion. Aqueous layer has become somewhat isstill very opaque. more transparent.

Alter 72 hours Cream 1% cc. Dark emul- Cream 1% ce. Homogension0.6 cc.thick. Aqueous cous opaque. No oil seplayer has become more eration.transparent. No oil separation.

AfterQhour-s Minute drops of oil have No oil separation.

4 separated in this emul- After 144 hours Cream on top 1% cc. than Creamon top 1% ce. Be-

ce. ot milky emulsion. mainingemulsionismillry he remainiu emulsionwhite as initial emulsion. is thin, trans uoent and No oil has yetseparated. v

brownish. Drops of oil on top.

While in the foregoing I have described the fractionation of oil solublesulphonic compounds ofthe type derived by sulphuric acid treatment ofcertain hydrocarbon oils, it shall be understood that my method is alsoapplicable to the fractionation of other oil soluble sulphonic compoundssuch as may be derived from certain fatt oils and/or fatty acids.

I claim as my invention:

1. -In the process of separating components of relatively high detergentand emulsifying properties from an oil-soluble substantially oil-freemixture of sulphonic compounds having varying detergent and emulsifyingproperties and solubilities in'hydrocarbon oils, the steps comprisingsubjecting said mixture to the action of two counterowing mutuallysubstantially immiscible organic solventsl a water-insoluble solvent,separable from sulphonic compounds by distillation, and awater-solublesolvent, under conditions to form two liquid phases with a.different solvent predominating in each phase and each phase containinga.v portion of sulphonic compounds of different composition from that ofthe other portion, separating the liquid phases and distllling the,phasewith predominating content of the water-insoluble solvent toseparate and recover the sulphonic compounds dissolved therein.

2. In the process of separating components of relatively high detergentand emulsifying properties from a substantially oil-free mixture ofsulphonic compounds having varying detergent and emulsifying propertiesand solubilities in hydro-V carbon' oils, obtained by sulphonating ahydrocarbon oil boiling above kerosene, the steps'comprising subjectingsaid substantially oil-free mixture to the simultaneous solvent actionof two mutually substantially immscible solvents, one of which is awater-insoluble solventseparable from sulphonic compounds bydistillation. and another is a. water-soluble solvent, under conditionsto f orm separate liquid phases, one containing substantial portions ofthe water-insoluble solvent and sulphonic compounds readily soluble lnhydrocarbonoils and possessing relatively high detergent and'emulslfyingproperties, and an' and emulsifying properties and solubilities inhydrocarbon oils, obtained by sulphonating a hydrocarbon oil boilingabove kerosene, the steps comprising dissolving said substantiallyoil-free mixture in an organic water-soluble solvent in which themixture is soluble and extracting the resulting solution with a.water-insoluble solvent which is separable from sulphonic compounds bydistillation and substantially immiscible with the water-solublesolvent, under conditions to form separate liquid phases, one containingsubstantial portions ofthe water-insoluble solvent and sulphoniccompounds readily soluble in hydrocarbon oils and possessing relativelyhigh detergent and emulsifying properties, and another one containingthe water-soluble solvent and the sulphonic compounds less readilysoluble in hydrocarbon oils, separating the phases and distilling theiirst phase to separate and recover the sulphonic compounds containedtherein.

4. In the process of separating components of relatively high detergentand emulsifying properties from a substantially oil-free mixture ofsulphonic compounds having varying detergent and emulsifying propertiesand solubilities in hydrocarbon oils, obtained by sulphonating ahydrocarbon oil boiling above kerosene, the steps comprislng dissolvingsaid mixture in an organic water-soluble solvent in whichthe mixture issoluble, subjecting the resultant solution to an extraction ofcounter-ilowing water and an organic water-insoluble solvent separablefrom the sulphonic Acompounds by distillation, the watersoluble andwater-insoluble solvents being substantially immiscible with each otherin the presence of said sulphonic compounds, under conditions to formtwo layers each of lwhich contains a material fraction of sulphoniccompounds originally contained in the mixture, separating the layers anddistilling the water-insoluble layer to separate and recover thesulphonic compounds dissolved therein.

5. The process of claim 2 in which the water-insoluble solventis anaromatic hydrocarbon solvent.

6. The process of claim 2 in whichthe waterinsoluble solvent is toluene.

'1. The process of claim 2 in which the watersoluble solvent containsanamount of water to render it substantially immiscible with the water-

